This invention relates to tools for establishing guides for placing or pouring concrete and similar work in new concrete construction such as a roadway, driveway, sidewalk, patio, bridges, decks, elevated floors, basements, parking lots and feedlots, or building floors.
In the past it was conventional practice to dig out the ground to a desired depth and then place a string line at the predetermined elevation of the finished concrete surface. Wooden stakes were then driven into the ground and pipes were laid horizontally on top of them. The upper surface of the pipes indicates the desired elevation of the finished concrete. Nails were driven into the stake tops on both sides of the pipe to keep it from rolling or being bumped off. The concrete was then poured or dumped into the desired area and struck or screed off with a strike board or screed on top of adjacent pipes. The pipes may be removed while the concrete is drying or setting and the indentations after removal of the pipes are then filled and the surface smoothed out, thus establishing a finished surface at the desired elevation of the concrete.
The use of wooden stakes with nails at their tops is inefficient, costly and time consuming compared to the material, tools and method of using them in the present invention. Wooden stakes are hard to drive so that their tops are at the required depth below the string line. They must be individually measured from the string line with a tape measure. The wooden stakes split easily when driven into the ground or when driving nails into them for holding the screed pipe. Often the accuracy is lost while driving nails stake tops in sand or soft soil conditions. In cold climates the wooden stakes swell in the concrete, causing cracks in the concrete.
To improve upon this these methods a device was formed that is seen in U.S. Pat. No. 5,173,004 to Fahrenkrog. The '004 patent presents a device with a leveling pin that was used to drive a conduit tube into the ground at a predetermined level. Then a yoke was placed in the tube so that a screed pipe conduit could be placed in the yoke at a desired location as compared to a concrete elevation finish line.
While this improved upon previous methods, problems still remain. Safety issues are presented because a user can hit his hand when driving the conduit through rock. In addition individuals desire to use other materials than conduit in concrete applications. These materials include rebar. Unfortunately, in the '004 design the driver is only effective at properly positioning a conduit. In addition the prior art assembly and method continue to have issues with cost in manufacturing the assembly.
Additional problems that need to be overcome include that current systems do not present a way to address different sizes of rebar or conduit. Further, utilizing a separate step of placing a yoke on or in a conduit after the conduit is driven in the group is time consuming and thus additional improvements are desired.
Thus, a principal object of the present invention is to provide an assembly that will account for different sizes of rebar.
Thus an object of the present invention is to provide a more efficient and accurate assembly for leveling concrete and sub-grade.
These and other objects, features, or advantages of the present invention will become apparent from the specification and the claims.